Power grid compensation device, substation system and power grid compensation control method

Abstract

The present application relates to a power grid compensation device, a substation system and a power grid compensation control method, including: a control unit, a twelve-switch power regulator, a first LC filter and a second LC filter; the control unit is connected to the control end of the twelve-switch power regulator; the first output end of the twelve-switch power regulator is connected to a target load through the first LC filter, and the second output end is connected to a target power supply through the second LC filter; the control unit performs pulse width modulation on the output of the first output end of the twelve-switch power regulator according to a first control strategy; the control unit performs pulse width modulation on the output of the second output end of the twelve-switch power regulator according to a second control strategy. The present application compensates and controls the voltage and current of the target power supply and the target load respectively through two independent output units, effectively simplifying the control logic while improving the reliability of the power grid system.

Description

Technical Field

[0001] The present application relates to the technical field of power grid compensation control, and in particular to a power grid compensation device, a substation system and a power grid compensation control method. Background Art

[0002] Most existing power conditioners adopt a back-to-back full-bridge converter structure, which requires a large number of semiconductor switches, usually 16, which makes the power conditioner costly and complex to control.

[0003] During the construction of a substation, the construction power supply is usually taken from the station transformer. Since most of the on-site construction tools use single-phase power, when the load is large, it is easy to cause the three-phase unbalanced load and excessive zero-sequence current of the station transformer. This situation may cause the switch to trip, or even trigger the zero-sequence protection of the station transformer, causing the 0.4kV busbar to lose pressure, posing a threat to the safe operation of the power station. Summary of the invention

[0004] Based on this, it is necessary to provide a power grid compensation device, a substation system and a power grid compensation control method that can reduce costs, simplify control logic, and effectively improve power grid reliability during substation construction to address the above technical problems.

[0005] In a first aspect, the present application provides a power grid compensation device, comprising: a control unit, a twelve-switch power regulator, a first LC filter and a second LC filter;

[0006] The control unit is connected to the control end of the twelve-switch power regulator;

[0007] The first output terminal of the twelve-switch power regulator is connected to a target load through the first LC filter;

[0008] The second output end of the twelve-switch power regulator is connected to the target power supply through the second LC filter;

[0009] The control unit performs pulse width modulation on the output of the first output terminal of the twelve-switch power regulator according to a first control strategy, wherein the first control strategy is used to generate a control action according to a reference current and a load current on one side of a target load;

[0010] The control unit performs pulse width modulation on the output of the second output terminal of the twelve-switch power regulator according to a second control strategy, wherein the second control strategy is used to generate a control action according to a reference voltage and a load voltage on one side of a target power supply.

[0011] In one embodiment, the twelve-switch power regulator includes a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a sixth switch tube, a seventh switch tube, an eighth switch tube, a ninth switch tube, a tenth switch tube, an eleventh switch tube, a twelfth switch tube, and a target capacitor;

[0012] Wherein, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, and the eighth switch tube form a first three-phase four-wire output unit;

[0013] The fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube form a second three-phase four-wire output unit;

[0014] The first three-phase four-wire output unit is also connected to the second three-phase four-wire output unit through the target capacitor;

[0015] The three-phase output terminals and the zero-phase output terminal of the first three-phase four-wire output unit are connected to the target load;

[0016] The three-phase output terminals and the zero-phase output terminal of the second three-phase four-wire output unit are connected to the target power supply.

[0017] In one embodiment, the control unit is respectively connected to the control electrodes of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube;

[0018] The input electrodes of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are all connected to one end of the target capacitor;

[0019] The output electrodes of the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube are all connected to the other end of the target capacitor;

[0020] The output terminal of the first switching tube is connected to the input terminal of the fifth switching tube, and the output terminal of the fifth switching tube is connected to the input terminal of the ninth switching tube; the output terminal of the second switching tube is connected to the input terminal of the sixth switching tube, and the output terminal of the fifth switching tube is connected to the input terminal of the tenth switching tube; the output terminal of the third switching tube is connected to the input terminal of the seventh switching tube, and the output terminal of the fifth switching tube is connected to the input terminal of the eleventh switching tube; the output terminal of the fourth switching tube is connected to the input terminal of the eighth switching tube, and the output terminal of the fifth switching tube is connected to the input terminal of the twelfth switching tube.

[0021] In one embodiment, the first LC filter includes multiple groups of resistors and capacitors connected in series;

[0022] The second LC filter includes multiple groups of resistors and capacitors connected in parallel.

[0023] In one embodiment, the control unit acquires the load current and the reference current;

[0024] Perform harmonic detection on the reference current to obtain the oscillating part of the load harmonics;

[0025] Perform proportional-integral control on the DC bus voltage to obtain a harmonic compensation component;

[0026] Perform harmonic compensation on the oscillating part according to the harmonic compensation component;

[0027] Calculate a first error signal according to the compensated reference current and the load current;

[0028] Process the first error signal according to a proportional-resonant controller to obtain a first control action;

[0029] Control the first three-phase four-wire output unit to perform pulse width modulation according to the first control action.

[0030] In one embodiment, the control unit acquires the load voltage and the reference voltage;

[0031] After performing low-pass filtering on the reference voltage by using a low-pass filter, calculate a second error signal according to the reference voltage and the load voltage;

[0032] Process the second error signal according to a proportional-resonant controller to obtain a second control action;

[0033] Control the second three-phase four-wire output unit to perform pulse width modulation according to the second control action.

[0034] In a second aspect, the present application further provides a substation system, including the grid compensation device, the target power supply, and the target load described in the first aspect;

[0035] The first output terminal of the twelve-switch power regulator of the power grid compensation device is connected to the target load through a first LC filter;

[0036] The second output terminal of the twelve-switch power regulator of the power grid compensation device is connected to the target power supply through a second LC filter.

[0037] In a third aspect, the present application also provides a power grid compensation control method, which is applied to the substation system described in the second aspect, and includes:

[0038] Performing pulse width modulation on the output of the first output terminal of the twelve-switch power regulator of the power grid compensation device according to a first control strategy, wherein the first control strategy is used to generate a control action according to a reference current and a load current on the target load side;

[0039] Performing pulse width modulation on the output of the second output terminal of the twelve-switch power regulator of the power grid compensation device according to a second control strategy, wherein the second control strategy is used to generate a control action according to a reference voltage and a load voltage on the target power supply side.

[0040] In one embodiment, the performing pulse width modulation on the output of the first output terminal of the twelve-switch power regulator of the power grid compensation device according to the first control strategy includes:

[0041] Obtaining the load current and the reference current;

[0042] Performing harmonic detection on the reference current to obtain an oscillating part of the load harmonics;

[0043] Performing proportional-integral control on the DC bus voltage to obtain a harmonic compensation component;

[0044] Performing harmonic compensation on the oscillating part according to the harmonic compensation component;

[0045] Calculating a first error signal according to the compensated reference current and the load current;

[0046] Processing the first error signal according to a proportional-resonant controller to obtain a first control action;

[0047] Performing pulse width modulation on the output of the first output terminal of the twelve-switch power regulator of the power grid compensation device according to the first control action.

[0048] In one embodiment, the performing pulse width modulation on the output of the second output terminal of the twelve-switch power regulator of the power grid compensation device according to the second control strategy includes:

[0049] Obtaining the load voltage and the reference voltage;

[0050] After performing low-pass filtering on the reference voltage using a low-pass filter, calculate a second error signal based on the reference voltage and the load voltage;

[0051] Process the second error signal according to a proportional-resonant controller to obtain a second control action;

[0052] Perform pulse-width modulation on the output of the second output terminal of the twelve-switch power regulator of the grid compensation device according to the second control action.

[0053] In summary, the present application proposes a grid compensation device, a substation system, and a grid compensation control method, including: a control unit, a twelve-switch power regulator, a first LC filter, and a second LC filter; the control unit is connected to the control terminal of the twelve-switch power regulator; the first output terminal of the twelve-switch power regulator is connected to a target load through the first LC filter, and the second output terminal is connected to a target power supply through the second LC filter; the control unit performs pulse-width modulation on the output of the first output terminal of the twelve-switch power regulator according to a first control strategy; the control unit performs pulse-width modulation on the output of the second output terminal of the twelve-switch power regulator according to a second control strategy. The present application compensates and controls the voltage and current of the target power supply and the target load through two independent output units, effectively simplifying the control logic while improving the reliability of the power grid system. Description of the Drawings

[0054] Figure 1 It is a block diagram of a grid compensation device in an embodiment;

[0055] Figure 2 It is a circuit schematic diagram of a twelve-switch power regulator in an embodiment;

[0056] Figure 3 It is an application circuit schematic diagram of a grid compensation device in an embodiment;

[0057] Figure 4 It is a schematic diagram of a first control strategy in an embodiment;

[0058] Figure 5 It is a schematic diagram of a second control strategy in an embodiment;

[0059] Figure 6 It is a schematic diagram of the method flow of a grid compensation control method in an embodiment;

[0060] Figure 7 It is a schematic diagram of the step flow of a grid compensation control method executing a first control strategy in an embodiment;

[0061] Figure 8 It is a schematic diagram of the step flow of a grid compensation control method executing a second control strategy in an embodiment.

[0062] Summary of the reference numerals:

[0063] Control unit - 110; Twelve-switch power regulator - 120; First LC filter - 130; Second LC filter - 140; Target load - 200; Target power supply - 300. Detailed implementation manners

[0064] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant accompanying drawings. Embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0065] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0066] It can be understood that the terms "first", "second", etc. used in the present application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of the present application, the first resistor can be called the second resistor, and similarly, the second resistor can be called the first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0067] It can be understood that in the following embodiments, "connection", if there is an electrical signal or data transmission between the connected circuits, modules, units, etc., should be understood as "electrical connection", "communication connection", etc.

[0068] It can be understood that "at least one" means one or more, and "a plurality" means two or more. "At least part of an element" means part or all of the element.

[0069] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms "comprising", "including" or "having", etc. specify the presence of the stated features, wholes, steps, operations, components, parts or combinations thereof, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0070] In the related art, three-phase balanced compensation technology often relies on additional hardware devices, such as additional filters or compensators, which increase the size and cost of the power grid or distribution station system.

[0071] Most power conditioners adopt a back-to-back full-bridge converter structure, which requires more semiconductor switches, such as 16 semiconductor switches, which greatly increases the cost and complexity of the grid compensation device.

[0072] Power regulators in related technologies usually use complex control strategies, such as pulse width modulation (PWM) technology, which requires precise timing control and high computing power, which inevitably increases the reliance on high-performance processors. In addition, due to the large number of semiconductor switches, the number of fault points increases.

[0073] The power conditioner in the related technology has low compensation efficiency for the voltage and current of the power grid in specific application scenarios such as substation construction. During the construction of the substation, since most of the on-site construction tools use unidirectional power supply, when the load is large, it is easy to cause unbalanced load and excessive zero-sequence current on the three-phase occupied transformer. This situation may cause the switch to trip or even trigger the zero-sequence protection of the substation transformer, causing the busbar to lose pressure, which has a great impact on the safe operation of the power station. In addition, the operation of the transformer in an unbalanced state may cause problems such as equipment overheating, voltage instability, and reduced motor efficiency. The existing power supply box and distribution panel are only equipped with protection circuits for branch leakage and overcurrent. These measures cannot effectively protect the operation risks of the transformer under unbalanced conditions.

[0074] This embodiment provides a power grid compensation device for addressing the three-phase imbalance problem in the substation construction power consumption scenario. By compensating for the unbalanced current of the single-phase load, the three-phase balance of the maintenance power box is achieved, the neutral line current and system losses are reduced, and the switch over-tripping problem caused by unidirectional load overcurrent is avoided, so as to improve the power supply safety and reliability of the substation construction devices.

[0075] like Figure 1 As shown, a power grid compensation device is provided, including: a control unit 110, a twelve-switch power regulator 120, a first LC filter 130, and a second LC filter 140. The control unit 110 is connected to the control end of the twelve-switch power regulator 120. The first output end of the twelve-switch power regulator 120 is connected to the target load 200 through the first LC filter 130. The second output end of the twelve-switch power regulator 120 is connected to the target power supply 300 through the second LC filter 140.

[0076] In this embodiment, the twelve-switch power regulator 120 includes twelve semiconductor switches. Compared with the power regulators in the related art, the number of semiconductor switches is effectively reduced, and the cost and control complexity of the power grid compensation device are reduced. In specific application scenarios, such as Figure 2 As shown, the twelve-switch power regulator 120 includes three parts, namely the top output unit (Top Unit), the intermediate switches, and the bottom output unit (Bottom Unit). Among them, are the four semiconductor switches of the top output unit, which are the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube from left to right. are the four semiconductor switches of the intermediate switches, which are the fifth switch tube, the sixth switch tube, the seventh switch tube, and the eighth switch tube from left to right. are the four semiconductor switches of the bottom output unit, which are the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube from left to right. , , , are the outputs of the top output unit (Top unit output), , , , are the outputs of the bottom output unit (Bottom unit output).

[0077] In this embodiment, the input poles of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are all connected to one end of the target capacitor. The output poles of the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube are all connected to the other end of the target capacitor. The output pole of the first switch tube is connected to the input pole of the fifth switch tube, and the output pole of the fifth switch tube is connected to the input pole of the ninth switch tube. The output pole of the second switch tube is connected to the input pole of the sixth switch tube, and the output pole of the fifth switch tube is connected to the input pole of the tenth switch tube. The output pole of the third switch tube is connected to the input pole of the seventh switch tube, and the output pole of the fifth switch tube is connected to the input pole of the eleventh switch tube. The output pole of the fourth switch tube is connected to the input pole of the eighth switch tube, and the output pole of the fifth switch tube is connected to the input pole of the twelfth switch tube.

[0078] It should be noted that the specific models and specifications of the switch tubes in the twelve-power regulator can be adaptively configured according to the needs of the actual application scenario. In this embodiment, the type of the switch tube is not specifically limited, and it can be adapted to any switch device in the market that can achieve the corresponding function, such as semiconductor switches, switch circuits, switch elements, etc.

[0079] In the actual application process, such as Figure 2 andFigure 3 As shown, the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube form a first three-phase four-wire output unit.

[0080] The fifth switching tube, the sixth switching tube, the seventh switching tube, the eighth switching tube, the ninth switching tube, the tenth switching tube, the eleventh switching tube and the twelfth switching tube form a second three-phase four-wire output unit.

[0081] The first three-phase four-wire output unit and the second three-phase four-wire output unit are interconnected by sharing an intermediate switching part, namely the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube. And the twelve-switch power regulator 120 further includes a target capacitor. The target capacitor can be a pulse capacitor or other capacitors available for storing electrical energy. As Figure 2 shown, the target capacitor is , and the target capacitor can be used to provide a DC bus voltage for the twelve-switch power converter . The first three-phase four-wire output unit is also connected to the second three-phase four-wire output unit through the target capacitor.

[0082] As Figure 3 shown, the three-phase output terminals and the zero-phase output terminal of the first three-phase four-wire output unit, namely , , and , are connected to the target load 200 through the first LC filter 130. In an actual application scenario, the target load 200 can be a non-linear unbalanced and critical load.

[0083] The three-phase output terminals and the zero-phase output terminal of the second three-phase four-wire output unit, namely , , and , are connected to the target power supply 300 through the second LC filter 140. In an actual application scenario, the three-phase output terminals and the zero-phase output terminal of the second three-phase four-wire output unit are connected to the transformer connected between the target power supply 300 and the target load 200 in the substation, so as to compensate and regulate the harmonics, voltage sags and surges in the grid voltage through the output of the second three-phase four-wire output unit.

[0084] In this embodiment, the first LC filter 130 includes multiple groups of resistors and capacitors connected in series. The second LC filter 140 includes multiple groups of resistors and capacitors connected in parallel. It should be noted that the actual connection positions of the first LC filter 130 and the second LC filter 140 can be configured according to the requirements of the actual application scenario. For example, as Figure 3 shown, the first LC filter 130 includes an inductor connected in series and a capacitor . Only one inductor is connected between the neutral line of the power grid and the neutral-phase output terminal of the first three-phase four-wire output unit . The second LC filter 140 includes an inductor and a capacitor connected in parallel . The three-phase output terminals of the second three-phase four-wire output unit are connected to one end of the secondary coil of the transformer in the three-phase power grid through an inductor and a capacitor connected in parallel . The other ends of the secondary coils are all connected to the neutral-phase output terminal of the second three-phase four-wire output unit.

[0085] In this embodiment, the control electrodes of the switching tubes of the twelve-switch power regulator 120 are all connected to the control unit 110. That is, the control unit 110 is respectively connected to the control electrodes of the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the fifth switching tube, the sixth switching tube, the seventh switching tube, the eighth switching tube, the ninth switching tube, the tenth switching tube, the eleventh switching tube, and the twelfth switching tube.

[0086] The control unit 110 performs pulse width modulation on the output of the first output terminal of the twelve-switch power regulator 120 according to the first control strategy, where the first control strategy is used to generate a control action based on the reference current and the load current on the target load 200 side.

[0087] The control unit 110 performs pulse width modulation on the output of the second output terminal of the twelve-switch power regulator 120 according to the second control strategy, where the second control strategy is used to generate a control action based on the reference voltage and the load voltage on the target power supply 300 side.

[0088] In this embodiment, the twelve-switch power regulator 120 is connected between the three-phase outgoing line of the maintenance power switch and the three-phase branch switch, and can dynamically monitor and respond to the unbalanced situation of the load current. By adjusting its working mode, the regulator can effectively compensate for the unbalanced current and achieve the balance of the three-phase circuit.

[0089] The twelve-switch power regulator 120 can be functionally divided into two independent three-phase four-wire output units. One three-phase four-wire output unit is connected in parallel with the target load 200 through a series LC filter and can be used to compensate for the current harmonics and unbalance of the target load 200. The other three-phase four-wire output unit is connected to the station transformer of the target power supply 300 of the distribution network through a parallel LC filter and is used to compensate for the harmonics, voltage sags, and surges in the grid voltage.

[0090] In this embodiment, the control unit 110 can be one or more. By connecting the control electrodes of the semiconductor switch tubes of the first three-phase four-wire output unit and the control electrodes of the semiconductor switch tubes of the second three-phase four-wire output unit through different control units 110 respectively, parallel compensation and series compensation can be realized respectively according to different control strategies. Among them, the first control strategy can be a parallel compensation strategy. The second control strategy can be a series compensation strategy.

[0091] In summary, this embodiment provides a power grid compensation device that realizes a dual-unit control strategy through the twelve-switch power regulator 120. The dual-unit control strategy significantly improves the stability of the power grid. Through real-time monitoring and dynamic adjustment, the power grid compensation device can quickly respond to voltage changes and current changes in the power grid and reduce the impacts caused by load fluctuations or power grid disturbances. Especially in scenarios such as substation construction, the unbalanced current of single-phase loads can be effectively compensated, avoiding problems such as equipment overheating and switch tripping caused by three-phase unbalance, thus ensuring the continuous and stable operation of the power grid.

[0092] In one of the embodiments, as Figure 4 shown, the first control strategy can be a parallel compensation control strategy. When the control unit 110 executes the first control strategy, the control unit 110 acquires the load current and the reference current; performs harmonic detection on the reference current to obtain the oscillating part of the load harmonics; performs proportional-integral control on the DC bus voltage to obtain a harmonic compensation component; performs harmonic compensation on the oscillating part according to the harmonic compensation component; calculates a first error signal according to the compensated reference current and the load current; processes the first error signal according to a proportional-resonant controller to obtain a first control action; and controls the first three-phase four-wire output unit to perform pulse width modulation according to the first control action.

[0093] In this embodiment, as Figure 4As shown, the first control strategy includes a DC bus voltage controller, a current reference generation module, a current controller, and a duty cycle modulation module for the first three-phase four-wire output unit. In the actual application process, the DC bus voltage controller is used to perform proportional-integral control on the DC bus voltage to obtain a harmonic compensation component. The current reference generation module is used to detect harmonics in the reference current to obtain the oscillating part of the load harmonics, and perform harmonic compensation on the oscillating part according to the harmonic compensation component. The current controller is used to calculate a first error signal based on the compensated reference current and the load current; process the first error signal according to a proportional-resonant controller to obtain a first control action. The duty cycle modulation module for the first three-phase four-wire output unit is used to control the first three-phase four-wire output unit to perform pulse-width modulation according to the first control action. An execution circuit and an execution program corresponding to the first control strategy are configured in the control unit 110.

[0094] In this embodiment, as Figure 3 and Figure 4 shown, when the control unit 110 executes the first control strategy, it first obtains currents and from the load side, where the current includes , , , , the current includes , , , , the current is the current output by the first three-phase four-wire output unit of the twelve-switch power regulator 120, and the current is the current received at the target load 200 terminal. In a specific application scenario, is the phase output current of the first three-phase four-wire output unit of the twelve-switch power regulator 120. is the phase output current of the first three-phase four-wire output unit of the twelve-switch power regulator 120. is the phase output current of the first three-phase four-wire output unit of the twelve-switch power regulator 120. is the zero-phase output current of the first three-phase four-wire output unit of the twelve-switch power regulator 120.

[0095] At the terminal of the target load 200 Connected to the received current At the terminal of the target load 200 Connected to the received current At the terminal of the target load 200 Connected to the received current Is the current received at the neutral terminal of the target load 200

[0096] When the control unit 110 obtains the reference current, it uses the current received at the terminal of the target load 200 As the reference current. The current output from the output terminal of the first three-phase four-wire output unit Is used as the load current

[0097] In this embodiment, after obtaining the reference current, the reference current in the three-phase stationary coordinate system (abc coordinate system) is converted into the d-axis component, q-axis component and 0-sequence component in the two-phase stationary coordinate dq coordinate system

[0098] For example, the reference current in the three-phase stationary coordinate system Is converted into the following in the dq coordinate system , And . In a specific implementation, this embodiment uses a phase-locked loop (PLL) to obtain the angular position of the grid voltage vector , for d-q transformation. It should be noted that the specific transformation method of d-q transformation can select a suitable transformation algorithm according to the needs of the actual application scenario, such as Clark transformation or Park transformation

[0099] The control unit 110 uses a high-pass filter (HPF) to filter the d-axis and q-axis reference current components to obtain the oscillating part of the load harmonics and compensate for the oscillating part. Among them, the superscript ~ represents the harmonic component obtained after being processed by the high-pass filter. Specifically, the control unit 110 obtains the actual value And the reference value Of the DC bus voltage, and performs proportional-integral control (PI control) on the actual value And the reference value Of the DC bus voltage to obtain the harmonic compensation component. The first control strategy in this embodiment ensures the stable operation of the power regulator under various load conditions by controlling the DC bus voltage

[0100] In this embodiment, after completing the harmonic compensation, the d-axis component, q-axis component and 0-sequence component of the reference current obtained after harmonic compensation are subjected to d-q inverse transformation to obtain the compensated reference current . For the load current Perform corresponding coordinate system transformation to obtain current . According to the reference current and current Calculate the first error signal, and input the first error signal into the proportional-resonant controller (PR Controllers). The first error signal is processed by the proportional-resonant controller to generate the first control action. The control unit 110 performs pulse width modulation (PWM) on the first three-phase four-wire output unit according to the first control action.

[0101] In one embodiment, as Figure 5 shown, the second control strategy can be a series compensation control strategy. When the control unit 110 executes the second control strategy, the control unit 110 obtains the load voltage and the reference voltage; after performing low-pass filtering on the reference voltage using a low-pass filter, calculate the second error signal according to the reference voltage and the load voltage; process the second error signal according to the proportional-resonant controller to obtain the second control action; control the second three-phase four-wire output unit to perform pulse width modulation according to the second control action.

[0102] As Figure 5 shown, the second control strategy includes a reference voltage generation module (Voltage referencegeneration), a voltage controller (Voltage controller), and a duty cycle modulation module for the second three-phase four-wire output unit (Duty cycles for PWM Bottom unit). In the actual application process, the reference voltage generation module is used to perform low-pass filtering on the reference voltage using a low-pass filter. The voltage controller is used to calculate the second error signal according to the reference voltage and the load voltage; process the second error signal according to the proportional-resonant controller to obtain the second control action. The duty cycle modulation module for the second three-phase four-wire output unit is used to control the second three-phase four-wire output unit to perform pulse width modulation according to the second control action. An execution circuit and an execution program corresponding to the second control strategy are configured in the control unit 110.

[0103] In this embodiment, as Figure 3 and Figure 5 shown, when the control unit 110 executes the second control strategy, it obtains the reference voltage and the load voltage from the grid side (the target power supply 300 side). The reference voltage is the voltage output by the target power supply 300. The load voltage is the voltage output by each phase output terminal of the second three-phase four-wire output unit of the twelve-switch power regulator 120.

[0104] Similar to the first control strategy in the foregoing embodiments, when executing the second control strategy, the control unit 110 converts the reference voltage and the load voltage into d-axis components, q-axis components, and zero-sequence components in the d-q coordinate system.

[0105] In this embodiment, the control unit 110 filters the reference voltage through a low-pass filter (LPF) to maintain stability during voltage sags or surges. Based on the filtered reference voltage and the load voltage obtained after corresponding coordinate system conversion processing the second error signal is calculated. The control unit 110 processes the second error signal with a proportional-resonant controller to generate a second control action, and the control unit 110 performs pulse-width modulation (PWM) on the second three-phase four-wire output unit according to the second control action.

[0106] In the actual application process, the second three-phase four-wire output unit can operate as a dynamic voltage restorer, responsible for compensating for harmonics, voltage sags or surges in the grid voltage to ensure that the load receives a sinusoidal voltage waveform.

[0107] Through the above control strategy, the twelve-switch power regulator 120 can effectively compensate for voltage and current imbalances in the grid, improve power quality, and ensure the stable operation of the load. The implementation of this control method relies on accurate monitoring, fast response, and precise control of the power regulator output.

[0108] In summary, this embodiment provides a grid compensation device that uses a proportional-resonant controller based on a stationary reference frame. This controller can accurately control the output of the twelve-switch power regulator to compensate for voltage and current problems in the grid. Through the first control strategy and the second control strategy in the foregoing embodiments, the system can ensure that the load receives a stable and distortion-free sinusoidal voltage waveform. Optimized power quality is crucial for ensuring the stable operation of electrical equipment and extending its service life. The embodiments of this application reduce the harmonic content of voltage and current, reducing the additional heat loss and mechanical stress generated by electrical equipment due to voltage distortion. In addition, a stable voltage supply also reduces the current impact during the startup and operation of electrical equipment, thereby improving the overall energy efficiency and reliability.

[0109] Secondly, the twelve-switch power regulator used in the power grid compensation device provided in this embodiment reduces the number of semiconductor switching tubes, thus simplifying the circuit topology. At the same time, the simplified control strategy reduces the need for complex calculations and precise timing control. The reduced number of semiconductor switches directly reduces the material cost and manufacturing cost. The simplified circuit design and control strategy also reduce the maintenance difficulty and maintenance cost of the system. In addition, the simplified design helps to improve the reliability of the system because fewer components mean fewer failure points. In terms of the control system, the simplified control strategy reduces the dependence on high-performance processors, further reducing costs and improving the operability and maintainability of the system.

[0110] A substation system is also provided, including the power grid compensation device, the target power supply, and the target load in the foregoing embodiment.

[0111] The first output terminal of the twelve-switch power regulator of the power grid compensation device is connected to the target load through a first LC filter.

[0112] The second output terminal of the twelve-switch power regulator of the power grid compensation device is connected to the target power supply through a second LC filter.

[0113] In this embodiment, the specific implementation manner of the substation system may refer to the specific implementation manner of the power grid compensation device in the foregoing device embodiment, and will not be elaborated here one by one.

[0114] In summary, this embodiment provides a substation system that uses a proportional-resonant controller based on a stationary reference frame. This controller can accurately control the output of the twelve-switch power regulator to compensate for voltage and current problems in the power grid. Through the first control strategy and the second control strategy in the foregoing embodiment, the system can ensure that the load receives a stable and distortion-free sinusoidal voltage waveform. Optimized power quality is crucial for ensuring the stable operation of electrical equipment and extending its service life. The embodiments of this application reduce the harmonic content of voltage and current, reducing the additional heat loss and mechanical stress generated by electrical equipment due to voltage distortion. In addition, a stable voltage supply also reduces the current impact during the startup and operation of electrical equipment, thereby improving the overall energy efficiency and reliability.

[0115] As Figure 6 shown, a power grid compensation control method is also provided, which is applied to the substation system in the foregoing embodiment and includes the following steps:

[0116] S601, perform pulse width modulation on the output of the first output terminal of the twelve-switch power regulator of the power grid compensation device according to the first control strategy, where the first control strategy is used to generate control actions according to the reference current and the load current on the target load side;

[0117] S602, perform pulse-width modulation on the output of the second output terminal of the twelve-switch power regulator of the power grid compensation device according to the second control strategy, where the second control strategy is used to generate a control action based on the reference voltage and the load voltage on the target power supply side.

[0118] In one embodiment, as Figure 7 shown, performing pulse-width modulation on the output of the first output terminal of the twelve-switch power regulator of the power grid compensation device according to the first control strategy includes:

[0119] S701, obtain the load current and the reference current;

[0120] S702, perform harmonic detection on the reference current to obtain the oscillating part of the load harmonics;

[0121] S703, perform proportional-integral control on the DC bus voltage to obtain a harmonic compensation component;

[0122] S704, perform harmonic compensation on the oscillating part according to the harmonic compensation component;

[0123] S705, calculate a first error signal based on the compensated reference current and the load current;

[0124] S706, process the first error signal according to a proportional-resonant controller to obtain a first control action;

[0125] S707, perform pulse-width modulation on the output of the first output terminal of the twelve-switch power regulator of the power grid compensation device according to the first control action.

[0126] In one embodiment, as Figure 8 shown, performing pulse-width modulation on the second three-phase four-wire output unit of the power regulator according to the second control strategy includes:

[0127] Performing pulse-width modulation on the output of the second output terminal of the twelve-switch power regulator of the power grid compensation device according to the second control strategy includes:

[0128] S801, obtain the load voltage and the reference voltage;

[0129] S802, after performing low-pass filtering on the reference voltage using a low-pass filter, calculate a second error signal based on the reference voltage and the load voltage;

[0130] S803, process the second error signal according to a proportional-resonant controller to obtain a second control action;

[0131] S804, perform pulse-width modulation on the output of the second output terminal of the twelve-switch power regulator of the power grid compensation device according to the second control action.

[0132] In summary, this embodiment provides a power grid compensation control method that uses a proportional-resonant controller based on a stationary reference frame. This controller can precisely control the output of a twelve-switch power regulator to compensate for voltage and current problems in the power grid. Through the first control strategy and the second control strategy in the foregoing embodiments, the system can ensure that the load receives a stable and distortion-free sinusoidal voltage waveform. Optimized power quality is crucial for ensuring the stable operation of electrical equipment and extending its service life. The embodiments of this application reduce the harmonic content of voltage and current, thereby reducing the additional heat loss and mechanical stress generated by electrical equipment due to voltage distortion. In addition, a stable voltage supply also reduces the current impact during the startup and operation of electrical equipment, thus improving the overall energy efficiency and reliability.

[0133] In the description of this specification, the descriptions referring to terms such as "some embodiments", "other embodiments", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0134] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0135] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A power grid compensation device, characterized in that Including: A control unit, a twelve-switch power regulator, a first LC filter, and a second LC filter; The control unit is connected to the control terminal of the twelve-switch power regulator; The first output terminal of the twelve-switch power regulator is connected to the target load through the first LC filter; the first LC filter includes multiple groups of resistors and capacitors connected in series; The second output terminal of the twelve-switch power regulator is connected to the target power supply through the second LC filter; the second LC filter includes multiple groups of resistors and capacitors connected in parallel; The control unit performs pulse width modulation on the output of the first output terminal of the twelve-switch power regulator according to a first control strategy, wherein the first control strategy is used to generate a control action based on a reference current and a load current on the target load side; the first control strategy is a shunt compensation control strategy; The control unit performs pulse width modulation on the output of the second output terminal of the twelve-switch power regulator according to a second control strategy, wherein the second control strategy is used to generate a control action based on a reference voltage and a load voltage on the target power supply side; the second control strategy is a series compensation control strategy; The twelve-switch power regulator includes a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a sixth switch tube, a seventh switch tube, an eighth switch tube, a ninth switch tube, a tenth switch tube, an eleventh switch tube, a twelfth switch tube, and a target capacitor; Wherein, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, and the eighth switch tube form a first three-phase four-wire output unit; The fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube form a second three-phase four-wire output unit; The first three-phase four-wire output unit is also connected to the second three-phase four-wire output unit through the target capacitor; The three-phase output terminals and the neutral output terminal of the first three-phase four-wire output unit are connected to the target load; The three-phase output terminals and the neutral output terminal of the second three-phase four-wire output unit are connected to the target power supply; The control unit is respectively connected to the control poles of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube; The input poles of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are all connected to one end of the target capacitor; The output poles of the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube are all connected to the other end of the target capacitor; The output terminal of the first switching tube is connected to the input terminal of the fifth switching tube, and the output terminal of the fifth switching tube is connected to the input terminal of the ninth switching tube; the output terminal of the second switching tube is connected to the input terminal of the sixth switching tube, and the output terminal of the fifth switching tube is connected to the input terminal of the tenth switching tube; the output terminal of the third switching tube is connected to the input terminal of the seventh switching tube, and the output terminal of the fifth switching tube is connected to the input terminal of the eleventh switching tube; the output terminal of the fourth switching tube is connected to the input terminal of the eighth switching tube, and the output terminal of the fifth switching tube is connected to the input terminal of the twelfth switching tube.

2. The power grid compensation device according to claim 1, characterized in that The control unit obtains the load current and the reference current; Performs harmonic detection on the reference current to obtain the oscillating part of the load harmonics; Performs proportional-integral control on the DC bus voltage to obtain a harmonic compensation component; Performs harmonic compensation on the oscillating part according to the harmonic compensation component; Calculates a first error signal based on the compensated reference current and the load current; Processes the first error signal according to a proportional-resonant controller to obtain a first control action; Controls the first three-phase four-wire output unit to perform pulse width modulation according to the first control action.

3. The power grid compensation device according to claim 1, characterized in that, The control unit obtains the load voltage and the reference voltage; After performing low-pass filtering on the reference voltage using a low-pass filter, calculates a second error signal based on the reference voltage and the load voltage; Processes the second error signal according to a proportional-resonant controller to obtain a second control action; Controls the second three-phase four-wire output unit to perform pulse width modulation according to the second control action.

4. A substation system, characterized in that, Includes the grid compensation device, the target power supply, and the target load according to any one of claims 1-3; The first output terminal of the twelve-switch power regulator of the grid compensation device is connected to the target load through a first LC filter; The second output terminal of the twelve-switch power regulator of the grid compensation device is connected to the target power supply through a second LC filter.

5. A power grid compensation control method, characterized in that, Applied to the substation system according to claim 4, includes: Performs pulse width modulation on the output of the first output terminal of the twelve-switch power regulator of the grid compensation device according to a first control strategy, wherein the first control strategy is used to generate a control action based on the reference current and the load current on the target load side; Performs pulse width modulation on the output of the second output terminal of the twelve-switch power regulator of the grid compensation device according to a second control strategy, wherein the second control strategy is used to generate a control action based on the reference voltage and the load voltage on the target power supply side.

6. The grid compensation control method according to claim 5, wherein, The performing pulse width modulation on the output of the first output terminal of the twelve-switch power regulator of the grid compensation device according to the first control strategy includes: Obtains the load current and the reference current; Performs harmonic detection on the reference current to obtain the oscillating part of the load harmonics; Performs proportional-integral control on the DC bus voltage to obtain a harmonic compensation component; Performs harmonic compensation on the oscillating part according to the harmonic compensation component; Calculates a first error signal based on the compensated reference current and the load current; Processes the first error signal according to a proportional-resonant controller to obtain a first control action; Perform pulse width modulation on the output of the first output terminal of the twelve-switch power regulator of the grid compensation device according to the first control action.

7. The grid compensation control method according to claim 5, wherein The performing pulse width modulation on the output of the second output terminal of the twelve-switch power regulator of the grid compensation device according to the second control strategy includes: Obtain the load voltage and the reference voltage; After performing low-pass filtering on the reference voltage by using a low-pass filter, calculate a second error signal according to the reference voltage and the load voltage; Process the second error signal according to a proportional-resonant controller to obtain a second control action; Perform pulse width modulation on the output of the second output terminal of the twelve-switch power regulator of the grid compensation device according to the second control action.

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